Gaseous fuel, on paper, looking bad (7)

I believe the answer is:

propane

I'm a little stuck... Click here to teach me more about this clue!

'gaseous fuel' is the definition.
(I've seen this before)

'on paper looking bad' is the wordplay.
'on paper' anagrams to 'PROPANE'.
But, I am not clear how the anagram is indicated.

Can you help me to learn more?

(Other definitions for propane that I've seen before include "Bottle gas" , "A hydrocarbon gas" , "Type of gas" , "Bottled fuel gas" , "Gas used as fuel" .)

I've seen this clue in The Times.

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